This is a Continuation of application Ser. No. 08/464,394 filed on Jun. 5, 1995, now abandoned.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to surface mounting type antenna systems, and more particularly to a surface mounting type antenna system for use in mobile radio communications and local area networks (LAN).
2. Description of the Related Art
FIG. 1 is a sectional view of a conventional surface mountingtype antenna system 90, whereinreference numeral 91 denotes an insulating material layer; 92, a flat-plate laminated coil; 93, a magnetic material layer; and 94a, 94b, external connection terminals.
Theantenna system 90 employs amorphous magnetic metal (relative permeability=104 to 105) for themagnetic material layer 93 to lower the resonance frequency by increasing the inductance of theantenna system 90.
However, the line length in the conventional surface mountingtype antenna system 90 is about (wavelength of resonant frequency)/10, which is less than (wavelength of resonant frequency)/4 in a dipole antenna. Therefore, the electrical volume and the gain have been small and poor. Moreover, the loss of the magnetic material layer tends to become greater at frequencies of over 100 MHz, thus making the magnetic material layer unusable at that frequency range.
Also, it is important that antennae for use in mobile radio communications and local area networks should be small-sized, and a normal-mode helical antenna represents one of those which satisfy such a demand. FIGS. 2, 3 and 4 illustrate the structure of such a normal surface mounting type antenna system.
FIG. 2 shows a normal-modehelical antenna 100a including alinear conductor 101 which is wound spirally so that itsspiral cross section 102 perpendicular to the axis C of winding is substantially circular, and apower supply member 103 which is situated at one end of theconductor 101, the other end being afree end 104.
FIG. 3 shows a normal-modehelical antenna 100b including alinear conductor 101 wound spirally so that itsspiral cross section 102 perpendicular to the axis C of winding is substantially circular, and apower supply member 103 situated substantially at the halfway point of theconductor 101, both ends of theconductor 101 being eachfree ends 104.
Further, FIG. 4 shows a normal-modehelical antenna 100c comprising alinear conductor 101 wound spirally so that itsspiral cross section 102 perpendicular to the axis C of winding is substantially rectangular, and apower supply member 103 situated substantially at the halfway point of theconductor 101, both ends of theconductor 101 being eachfree ends 104.
However, each of the normal-modehelical antennae 100a to 100c provides no sensitivity to dominant and cross polarized waves from the direction of the axis C of the conductor winding 101 but sensitivity thereto from the direction perpendicular to the axis C of the conductor winding 101 (the VV direction in FIGS. 2 to 4).
Therefore, transmission and reception are impossible in a case where the transmission of dominant and cross polarized waves are made in such a state that the normal-modehelical antennae 100a to 100c tilt at 90°; the problem is that the sensitivity is dependent on their postures.
SUMMARY OF THE INVENTIONThe present invention has been made to solve the foregoing problems, and an object of the invention is to provide a surface mounting type antenna system which provides a high gain and is free from dependence on its posture.
Another object of the invention is to provide a compact surface mounting type antenna system for yielding not only sensitivity to dominant and cross polarized waves in at least both directions: the direction of and a direction perpendicular to, the axis of conductor winding but also that is free from dependence on its posture.
In order to solve the aforementioned problems, a first aspect of the invention has been achieved by the provision of a surface mounting type antenna system which comprises a dielectric substrate, and a conductor which is wound spirally on the surface or in the dielectric substrate. Further, at least a power supply terminal for use in applying voltage to the conductor is provided on the surface of the dielectric substrate.
A fixing terminal for securing the dielectric substrate onto the surface of a mounting board is also provided onto the surface of the dielectric substrate.
The spiral conductor squarely intersecting the axis of the conductor winding partly includes at least a linear portion in transverse cross section.
Further, in order to solve the above-mentioned problems, a second aspect of the invention has been achieved by the provision of an antenna which comprises a conductor which is wound spirally, and a power supply member provided at one end of the conductor, the other end thereof being a free end, wherein the sensitivity of the antenna to dominant and cross polarized waves is provided in at least both directions: the direction of and a direction perpendicular to, the axis of conductor winding.
Moreover, the spiral conductor squarely intersecting the axis of the conductor winding partly includes at least a linear portion in transverse cross section.
Further, the conductor is provided on the surface of or in a dielectric substrate.
According to the surface mounting type antenna system of the invention, the propagation velocity becomes slow, whereas wavelength contraction occurs as the antenna systems incorporates the dielectric substrate, whereby an effective line length is rendered .di-elect cons.1/2 times greater, where .di-elect cons.=dielectric constant of the dielectric substrate.
Also, according to the surface mounting type antenna system of the invention, the provision of the fixing terminal allows the dielectric substrate to be secured onto the surface mounting board with stability.
Further, according to the surface mounting type antenna system of the invention, since the conductor squarely intersecting the axis of the winding is substantially rectangular in transverse cross section including the linear portion in part, the line length of the antenna can be made greater than that of an antenna whose spiral conductor is substantially circular or elliptical in transverse cross section on the assumption that their transverse cross-sectional areas are equal.
According to the helical antenna of the invention, it is feasible to obtain sensitivity substantially equal to that of a dipole antenna, that is, sensitivity to dominant and cross polarized waves and sensitivity at a level at which transmission and reception are possible.
The above and other objects and features of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a perspective view showing a conventional surface mounting type antenna system;
FIG. 2 is a perspective view showing a conventional helical antenna;
FIG. 3 is a perspective view showing another conventional helical antenna;
FIG. 4 is a perspective view of still another conventional helical antenna;
FIG. 5 is a perspective view showing a surface mounting type antenna system according to a first embodiment of the present invention;
FIG. 6 is a perspective view showing a surface mounting type antenna system according to a second embodiment of the present invention;
FIG. 7 is a perspective view showing a surface mounting type antenna system according to a third embodiment of the present invention;
FIG. 8 is a perspective view showing a surface mounting type antenna system according to a fourth embodiment of the present invention;
FIG. 9 is an exploded perspective view showing the surface mounting type antenna system of FIG. 8;
FIG. 10 is a perspective view showing a surface mounting type antenna system according to a fifth embodiment of the present invention;
FIG. 11 is a perspective view showing a surface mounting type antenna system according to a sixth embodiment of the present invention;
FIG. 12 is a perspective view showing a surface mounting type antenna system according to a seventh embodiment of the present invention;
FIG. 13 is a perspective view showing a surface mounting type antenna system according to an eighth embodiment of the present invention;
FIG. 14 is an exploded perspective view showing the surface mounting type antenna system of FIG. 13;
FIG. 15 is a chart illustrating the sensitivity of the surface mounting type antenna system of FIG. 5 to a dominant polarized wave in the direction of x-axis;
FIG. 16 is a chart illustrating the sensitivity of the surface mounting type antenna system of FIG. 5 to a cross polarized wave in the direction of x-axis;
FIG. 17 is a chart illustrating the sensitivity of the surface mounting type antenna system of FIG. 5 to the dominant polarized wave in the direction of y-axis;
FIG. 18 is a chart illustrating the sensitivity of the surface mounting type antenna system of FIG. 5 to the cross polarized wave in the direction of y-axis;
FIG. 19 is a chart illustrating the sensitivity of the surface mounting type antenna system of FIG. 5 to the dominant polarized wave in the direction of z-axis;
FIG. 20 is a chart illustrating the sensitivity of the surface mounting type antenna system of FIG. 5 to the cross polarized wave in the direction of z-axis;
FIGS. 21A and 21B are diagrams illustrating spiral conductors of surface mounting type antenna systems according to the present invention, in which FIG. 21A is a spiral conductor having a substantially track-like transverse cross section; and FIG. 21B is a spiral conductor having a substantially semicylindrical transverse cross section;
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTSReferring to the drawings, a description will subsequently be given of embodiments of the present invention, wherein like reference characters designate like or corresponding component parts in a first embodiment of the invention and the description thereof will be omitted.
FIG. 5 is a perspective view showing a first surface mounting type antenna system embodying the present invention. A surface mountingtype antenna system 10 is formed by spirally winding aconductor 14 made of copper or copper alloy, with apower supply member 12 provided at one end of theconductor 14, the other end thereof being afree end 13, on the edge faces of a rectangular parallelepiped as adielectric substrate 11 by printing, deposition, pasting or plating. Thedielectric substrate 11 is prepared by stacking a plurality of layers of mixed material mainly containing barium oxide, aluminum oxide and silica, or resin, for example, teflon resin, or a combination of ceramics and resin. In this case, theconductor 14 is wound in the direction of height of the dielectric substrate 11 (in the direction of arrow H in FIG. 5).
On theunderside 111 of thedielectric substrate 11 lies apower supply terminal 15 to which thepower supply member 12 of theconductor 14 is connected. Thepower supply terminal 15 is simultaneously used as a fixing terminal for securing the surface mountingtype antenna system 10 to a mounting part (not shown) provided with an external circuit. In this practice of the invention, thedielectric substrate 11 may be formed by stacking a plurality of dielectric substrate layers or otherwise formed with, for example, one sheet of dielectric substrate layer. At this time, theconductor 13 squarely intersecting the axis A of the conductor winding 13 is rectangular intransverse cross section 14 having a width of w and a length of l.
Now the line length of the surface mountingtype antenna system 10 in this practice of the invention is compared with that of a conventional normal-mode helical antenna (radius: a) whose spiral conductor is circular in transverse cross section.
Assuming that the transverse cross-sectional area S perpendicular to the axis of the winding and the number of turns N are constant, the transverse cross-sectional areas S which are rectangular and circular are each expressed by
in the rectangular case: S=w×l; and
in the circular case: S=πa2.
Since the line length is the outer periphery of the spiral cross section×N, the rectangular and circular line lengths l1, l2 are each given by
in the rectangular case: l1 =2×(w+l)×N; and
in the circular case: l2 =2×(π×w×l)1/2 ×N.
Consequently, the line length l1 of the surface mountingtype antenna system 10 rectangular in transverse cross section in this practice of the invention is proved longer.
Further, measurement was made of the sensitivity of the surface mountingtype antenna system 10 in the directions of x-, y- and z- axes.
FIGS. 15 through 20 show the sensitivity of the surface mountingtype antenna system 10, wherein there is shown sensitivity to dominant and cross polarized waves in the directions of x-axes, sensitivity to dominant and cross polarized waves in the directions of y-axes, and sensitivity to dominant and cross polarized waves in the directions of z-axes, respectively.
It was also proved from the measured results of sensitivity that the surface mountingtype antenna system 10 functioned almost non-directionally as it had shown sensitivity to the dominant and cross polarized waves in not only the direction perpendicular to the axis A of the winding, that is, in the directions of y- and z-axes but also the direction of the axis A of the winding, that is, in the direction of x-axis.
Although a description has been given of the case where theconductor 14 is formed by printing, deposition, pasting or plating in the practice of the invention above, a spiral groove may be made in thedielectric substrate 11 so as to wind a plated or enameled wire along the groove.
Since theconductor 14 squarely intersecting the axis A of the winding is rectangular intransverse cross section 16 in the first embodiment of the invention as set forth above, the line length can be made greater than that of the circular or elliptical conductor. Therefore, an area of current distribution is increased further and the quantity of electric waves thus radiated is also increased further, so that the antenna gain is made improvable thereby further.
The surface mountingtype antenna system 10 functions almost non-directionally and thus has sensitivity to dominant and cross polarized waves in the three directions of x-, y- and z-axes, so that transmission and reception become possible, irrespective of the position of the mobile communications apparatus. As a result, the sensitivity of the surface mountingtype antenna system 10 independent of its posture.
Moreover, a propagation velocity becomes slow, whereas wavelength contraction occurs, whereby an effective line length is rendered .di-elect cons.1/2 times greater, where .di-elect cons.=dielectric constant of the dielectric substrate. The effective line length becomes greater than that of the conventional surface mounting type antenna system. Therefore, an area of current distribution is increased and the quantity of electric waves thus radiated is also increased, so that the antenna gain is made improvable thereby.
If characteristics similar to those of the conventional surface mounting type antenna system are conversely desired, moreover, the line length will be reduced to 1/.di-elect cons.1/2. It is therefore possible to reduce the size of the surface mountingtype antenna system 10.
Since theconductor 14 is wound in the direction of height of thedielectric substrate 11, further, the number of turns can be decreased by increasing the transverse cross-sectional area S squarely crossing the axis A of the winding. Consequently, the height of the surface mountingtype antenna system 10 is reducible.
FIG. 6 is a perspective view of a second surface mounting type antenna system embodying the present invention. A surface mountingtype antenna system 20 is formed by spirally winding theconductor 14 by printing, deposition, pasting or plating, along the inner walls of acavity 22 provided in adielectric substrate 21 made of ceramics, resin or a combination of ceramics and resin. As in the first embodiment of the invention, theconductor 14 is wound in the direction of height of thedielectric substrate 21 at this time.
As set forth above, theconductor 14 is not exposed on the edge faces of thedielectric substrate 21 in the second embodiment of the invention, which makes this surface mounting type antenna system easy to handle in addition to making achievable the same effect as that of the first surface mountingtype antenna system 10 according to the present invention likewise.
FIG. 7 is a perspective view of a third surface mounting type antenna system embodying the present invention. As in the first embodiment of the invention, a surface mountingtype antenna system 30 is formed by spirally winding theconductor 14 on the edge faces of thedielectric substrate 11 and sealing up theconductor 14 in adielectric substrate 31 made of ceramics, resin or a combination of ceramics and rein. As in the first embodiment of the invention, theconductor 14 is wound in the direction of height of thedielectric substrate 21.
As set forth above, theconductor 14 is sealed up in thedielectric substrate 31 in the third embodiment of the invention, whereby in comparison with the second embodiment of the invention, the wavelength is decreased further and the effective line length of the surface mountingtype antenna system 30 is also increased further. Therefore, an area of current distribution is increased further and the quantity of electric waves thus radiated is also increased further, so that the antenna gain is made improvable thereby further.
FIGS. 8 and 9 are perspective views of a fourth surface mounting type antenna system embodying the present invention. A surface mountingtype antenna system 40 is formed by spirally winding aconductor 44 made of copper or copper alloy, with a power supply member 42 provided at one end of theconductor 44, the other end thereof being afree end 43, in a rectangular parallelepiped as adielectric substrate 41. Thedielectric substrate 41 is prepared by stacking a plurality of layers of ceramics, resin or a combination of ceramics and resin. In this case, theconductor 44 is wound in the direction of height of the dielectric substrate 41 (in the direction of arrow H in FIG. 5) as in the first embodiment of the invention.
The conductor 42 is formed into a spiral through the steps of providingconductor patterns 45 each on the surfaces of dielectric substrate layers 41b to 41f constituting thedielectric substrate 41 by printing, vapor deposition, pasting or plating, stacking thedielectric substrate layers 41a to 41f, and coupling theconductor patterns 45 withpierced holes 46.
As set forth above, the laminated structure employed for the fourth surface mountingtype antenna system 40 according to the present invention makes formable a compact inexpensive surface mounting type antenna system in addition to making obtainable the same effect as that of the third surface mountingtype antenna system 30.
FIG. 10 is a perspective view of a fifth surface mounting type antenna system embodying the present invention. A surface mountingtype antenna system 50 is formed by spirally winding theconductor 14 on the edge faces of a rectangular parallelepiped as adielectric substrate 51 by printing, deposition, pasting or plating. Thedielectric substrate 51 is prepared by stacking a plurality of layers of ceramics, resin or a combination of ceramics and resin. In this case, theconductor 14 is wound in the longitudinal direction of the dielectric substrate 51 (in the direction of an arrow L in FIG. 10).
Thepower supply terminal 15 is formed on oneedge face 511 of thedielectric substrate 51 and thepower supply member 12 of theconductor 14 is connected to theedge face 511. A fixingterminal 52 for securing the surface mountingtype antenna system 50 to a mounting board (not shown) provided with an external circuit is formed on theopposite edge face 512.
Although a description has been given of the case where theconductor 14 is formed by printing, deposition, pasting or plating in the practice of the invention above, a spiral groove may be made in thedielectric substrate 51 so as to wind a plated or enameled wire directly along the groove of thedielectric substrate 51 as in the first embodiment of the invention.
Since theconductor 14 is wound in the longitudinal direction of thedielectric substrate 51 in the fifth embodiment of the invention as set forth above, the winding pitch P can be set greater. Therefore, the inductance of the surface mountingtype antenna system 50 can also be lowered, so that the surface mountingtype antenna system 50 can operate at a frequency of 1 GHz or higher.
Moreover, the provision of the fixingterminal 52 makes it possible to mount the antenna system with stability when it is surface-mounted.
FIG. 11 is a perspective view of a sixth surface mounting type antenna system embodying the present invention. A surface mountingtype antenna system 60 is formed by spirally winding theconductor 14 by printing, deposition, pasting or plating, along the inner walls of a cavity 62 provided in adielectric substrate 61 made of ceramics, resin or a combination of ceramics and resin. As in the fifth embodiment of the invention, theconductor 14 is wound in the longitudinal direction of thedielectric substrate 61 at this time.
As set forth above, theconductor 14 is not exposed on the edge faces of thedielectric substrate 61 in the sixth embodiment of the invention, which makes this surface mountingtype antenna system 50 easy to handle in addition to making achievable the same effect as that of the fifth surface mounting type antenna system according to the present invention likewise.
FIG. 12 is a perspective view of a seventh surface mounting type antenna system embodying the present invention. As in the fifth embodiment of the invention, a surface mounting type antenna system 70 is formed by spirally winding theconductor 14 on the edge faces of thedielectric substrate 51 and sealing up theconductor 14 in adielectric substrate 71 made of ceramics, resin or a combination of ceramics and resin. As in the fifth embodiment of the invention, theconductor 14 is wound in the longitudinal direction of thedielectric substrate 71.
As set forth above, theconductor 14 is sealed up in thedielectric substrate 71 in the seventh embodiment of the invention, whereby in comparison with the fifth embodiment of the invention, the wavelength is decreased further and the effective line length of the surface mounting type antenna system 70 is also increased further. Therefore, an area of current distribution is increased further and the quantity of electric waves thus radiated is also increased further, so that the antenna gain is made improvable thereby further.
FIGS. 13 and 14 are perspective views of an eighth surface mounting type antenna system embodying the present invention. A surface mounting type antenna system 80 is formed by spirally winding aconductor 84 made of copper or copper alloy, with apower supply member 82 provided at one end of theconductor 84, the other end thereof being afree end 83, in a rectangular parallelepiped as adielectric substrate 81. Thedielectric substrate 81 is prepared by stacking a plurality of layers of ceramics, resin or a combination of ceramics and resin. In this case, theconductor 84 is wound in the longitudinal direction of thedielectric substrate 81 as in the fifth embodiment of the invention.
Theconductor 84 is formed into a spiral through the steps of providingconductor patterns 85 each on the surfaces of dielectric substrate layers 81b and 81c constituting adielectric substrate 81 by printing, deposition, pasting or plating, stacking thedielectric substrate layers 81a to 81c, and coupling theconductor patterns 85 withpierced holes 86.
As set forth above, the laminated structure employed for the eighth surface mounting type antenna system 80 according to the present invention makes formable a compact inexpensive surface mounting type antenna system in addition to making obtainable the same effect as that of the seventh surface mounting type antenna system 70.
Although a description has been given of the case where the spiral conductor is rectangular in transverse cross section, it may be in the shape of substantially a track having two straight lines and two curved lines, or a semicylinder having one straight line and one curved line as shown in FIGS. 21A and 21B; that is, it may be in any shape having at least one straight line.
With respect to the spiral configurations, the combination of rectangles substantially similar in transverse cross section have been used to constitute the conductor. However, a combination of those which include at least a linear portion in part and are different in transverse cross section may also be employed.
For example, the conductor may be made spiral in such a manner that its traverse cross sectional size is gradually increased or decreased toward the free end from the power supply member.
Although copper or copper alloy has been used to form the conductor, it may also be gold, silver, platinum, vanadium or the like as long as it is a low-resistant conductor.
Although a description has been given of the case where the dielectric substrate is a rectangular parallelepiped, it may also be a solid sphere, a regular hexahedron, a circular cylinder, a circular cone or a pyramid.
According to the surface mounting type antenna system of the present invention, the surface mounting type antenna system functions almost non-directionally and thus has sensitivity to dominant and cross polarized waves in the three directions of x-, y- and z-axes, so that transmission and reception become possible, irrespective of the position of the mobile communications apparatus. As a result, the sensitivity of the surface mounting type antenna system is independent of dependence on its posture.
Since a dielectric substrate is used, propagation velocity becomes slow, whereas wavelength contraction occurs, whereby an effective line length is rendered .di-elect cons.1/2 times greater, where .di-elect cons.=dielectric constant of the dielectric substrate. The effective line length becomes greater than that of the conventional surface mounting type antenna system. Therefore, an area of current distribution is increased and the quantity of electric waves thus radiated is also increased, so that the antenna gain is made improvable thereby.
If characteristics similar to those of the conventional surface mounting type antenna system are conversely desired, moreover, the line length will be reduced to 1/.di-elect cons.1/2. It is therefore possible to reduce the size of the surface mounting type antenna system.
According to the surface mounting type antenna system of the present invention, the provision of the fixing terminal makes it possible to mount the antenna system with stability when it is surface-mounted.
According to the surface mounting type antenna system of the present invention, since the spiral conductor squarely intersecting the axis of the winding is substantially rectangular in transverse cross section including the linear portion in part, the line length of the antenna can be made greater than that of an antenna whose spiral conductor is substantially circular or elliptical in transverse cross section on the assumption that their transverse cross-sectional areas are equal. Therefore, an area of current distribution is increased further and the quantity of electric waves thus radiated is also increased further, so that the antenna gain is made improvable thereby further.
The foregoing description of the preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents.